Electric vacuum cleaner

ABSTRACT

Provided are rotary brush unit which is disposed inside suction port portion and in which two rotary shaft bodies each having brush are disposed in series and driving motor which separately rotates each of the rotary shaft bodies. With such a configuration, since it is possible to change a self-propelling direction of the suction port portion to the left and right direction in addition to the forward direction, it is possible to remarkably reduce the effort involved in an operation of changing the direction of the suction port portion.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Japanese PatentApplication No. JP2008-282714 filed on Nov. 4, 2008, the entire contentof which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an electric vacuum cleaner having asuction port portion and a handle portion.

BACKGROUND ART

In an existing electric vacuum cleaner, dust collecting performanceusing a sweeping-up rotary brush is good in regards to a floor surfaceand particularly a carpet surface. However, since the electric vacuumcleaner is equipped with a motor for driving the rotary brush, it isdisadvantageous in that the suction port portion easily becomes heavyand the cleaning operation is wearisome. In order to solve thedisadvantage, for example, Japanese Patent Unexamined Publication No.2-7923 discloses a technology in which a suction port portion isprovided with a self-propelling roller or a rotary brush itself isactively brought into contact with a floor surface so as to have aself-propelling property.

However, in the above-described technology, it is possible to reduce theeffort upon operating the suction port portion forward or backward, butit is necessary to change a direction of the suction port portion bytwisting a wrist upon changing the direction in the left and rightdirection. For this reason, it is not possible to reduce the effortinvolved. Particularly, in an upright cleaner having a heavy suctionport portion, it takes a good deal of effort to change the direction ofthe suction port portion. Since the direction of the suction portportion is frequently changed during an actual cleaning operation,particularly at this time, a large burden is applied to the wrist. As aresult, the wrist feels fatigued after a long-time cleaning operation.

SUMMARY OF THE INVENTION

An object of the invention is to provide an electric vacuum cleanercapable of changing a direction of a suction port portion to a desiredchanging direction and reducing the burden applied to a user's wrist.

According to an aspect of the invention, there is provided an electricvacuum cleaner including: a cleaner body portion which has an electricblower for generating a suction wind; a suction port portion which sucksdust together with the suction wind; a handle portion which moves thesuction port portion; a rotary brush unit which is disposed inside thesuction port portion and in which two rotary shaft bodies each having abrush are disposed in series; a rotary brush unit driving portion whichseparately rotates each of the rotary shaft bodies; and a rotation speeddifference generating mechanism which generates a difference in therotation speed between two rotary shaft bodies.

According to the invention, the rotary brush unit includes two rotaryshaft bodies, and the rotation speed difference generating mechanismgenerates a difference in the rotation speed between two rotary shaftbodies. For this reason, it is possible to easily change the directionof the suction port portion to the desired changing direction.Accordingly, since it is possible to remarkably reduce a burden during acleaning operation, it is possible to more comfortably perform thecleaning operation which is a comparatively heavy labor in thehousework.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an entire perspective view showing a cleaner body portion ofan electric vacuum cleaner according to a first embodiment of theinvention.

FIG. 2 is a partially sectional view showing a suction port portionaccording to the embodiment.

FIG. 3 is a block diagram showing a configuration of an electriccontroller according to the embodiment.

FIG. 4 is an entire perspective view showing the cleaner body portion ofthe electric vacuum cleaner according to a second embodiment of theinvention.

FIG. 5 is a plan view showing a rotary brush unit of the electric vacuumcleaner according to a third embodiment of the invention.

FIG. 6 is a plan view showing the rotary brush unit of the electricvacuum cleaner according to a fourth embodiment of the invention.

FIG. 7 is a plan view showing the rotary brush unit of the electricvacuum cleaner according to a fifth embodiment of the invention.

FIG. 8 is a plan view showing the rotary brush unit of the electricvacuum cleaner according to a sixth embodiment of the invention.

FIG. 9 is a plan view showing the rotary brush unit of the electricvacuum cleaner according to a seventh embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments of the invention will be describedwith reference to the accompanying drawings. In addition, the inventionis not limited to the embodiments.

First Embodiment

FIG. 1 is an entire perspective view showing a cleaner body portion ofan electric vacuum cleaner according to a first embodiment of theinvention. FIG. 2 is a partially sectional view showing a suction portportion according to the embodiment when seen from the bottom of thesuction port portion.

As shown in FIG. 1, an electric vacuum cleaner according to thisembodiment includes suction port portion 1 which sucks dust, handleportion 11 which moves suction port portion 1, and cleaner body portion12 of which a lower portion is provided with suction port portion 1 andan upper portion is provided with handle portion 11. Cleaner bodyportion 12 includes an electric blower for generating a suction wind.Suction port portion 1 sucks dust together with the suction windgenerated by the electric blower. Switch lever portion 10 is attachedonto handle portion 11. Switch lever portion 10 is attached to aposition where switch lever portion 10 is operable by a finger whengripping handle portion 11 using a hand. When switch lever portion 10 ispushed down in the left and right direction, as depicted by the arrow,suction port portion 1 is controlled so that the direction thereof ischanged to the direction in which switch lever portion 10 is pusheddown.

As shown in FIG. 2, rotary brush unit 2 is disposed inside suction portportion 1. Rotary brush unit 2 includes two rotary shaft bodies 2A and2B. Brush 3 is disposed in surfaces of rotary shaft bodies 2A and 2B.

In FIG. 2, brush 3 is formed as a so-called bristle transplant brush inwhich bristles are tied and transplanted inside a hole, but may beformed as a brush in which a narrow raised fabric is inserted and fixedinto an undercut groove or a bonded brush.

Each of the rotary shaft bodies 2A and 2B is provided with driving motor4 and decelerating gear 5. Driving motor 4 is connected to deceleratinggear 5 to thereby form a rotary brush unit driving portion. An outputshaft of decelerating gear 5 is fixed to each of rotary shaft bodies 2Aand 2B. With such a configuration, when driving motors 4 are driven,rotary shaft bodies 2A and 2B located in the peripheries thereof rotate.

Likewise, a rotary mechanism is constituted by only rotary brush unit 2in such a manner that driving motor 4 and decelerating gear 5 aredisposed inside each of rotary shaft bodies 2A and 2B. Accordingly, itis not necessary to dispose a large component such as a driving motor inthe inside of suction port portion 1. For this reason, it is possible todecrease the size of suction port portion 1. That is, it is possible torealize suction port portion 1 which can move and turn slightly and hasgood operability or cleaner body portion 12 which is small in size andlow in weight.

The length of brush 3 is set to a length at which brush 3 slightly comesinto contact with a floor surface. For this reason, when rotary shaftbodies 2A and 2B rotate in a direction (positive direction) in whichsuction port portion 1 is pushed forward, suction port portion 1 propelsitself, thereby improving the operability of cleaner body portion 12.That is, when driving motors 4 inside rotary shaft bodies 2A and 2Brotate at the same speed (including substantially the same speed) in thesame direction (positive direction), suction port portion 1 propelsitself forward.

In addition, each of rotary shaft bodies 2A and 2B is driven by aseparate driving motor 4. For this reason, it is possible toindependently change the rotation speeds thereof. When the right drivingmotor on the user side rotates faster than the left driving motor oronly the right driving motor rotates, a direction of suction portportion 1 is changed to the left direction. On the other hand, when theleft driving motor rotates faster than the right driving motor or onlythe left driving motor rotates, the direction of suction port portion 1is changed to the right direction.

In addition, when the driving motor located in the desired rotationdirection rotates in the reverse direction and the opposite drivingmotor rotates in the positive direction, it is possible to furtherstrongly change the direction of suction port portion 1.

Switch lever portion 10 controls driving motors 4 inside rotary shaftbodies 2A and 2B through the electric controller shown in FIG. 3. FIG. 3is a block diagram showing a circuit of the electric vacuum cleaneraccording to this embodiment. In FIG. 3, motor 35 for driving theelectric blower generating the suction wind is connected in parallel toAC power source 36. Power switch portion 37 controlling an on-off stateof motor 35 is disposed close to handle portion 11 of cleaner bodyportion 12 (not shown in FIG. 1). Driving motor 38A (one driving motor 4shown in FIG. 2) for driving rotary shaft body 2A is connected in seriesto rotary shaft body switch portion 39A for controlling the on-off stateof driving motor 38A. In the same manner, driving motor 38B (the otherdriving motor 4 shown in FIG. 2) for driving rotary shaft body 2B isconnected in series to rotary shaft body switch portion 39B forcontrolling an on-off state of driving motor 38B. The two serialconnection portions are connected in parallel to motor 35. Rotary shaftbody switch portions 39A and 39B are operated in an interlocking manneras depicted by the dotted line by switch lever portion 10.

In the normal state where no operation is performed, switch leverportion 10 turns on rotary shaft body switch portions 39A and 39B, androtates driving motors 38A and 38B at the same speed in the samedirection (positive direction). Accordingly, suction port portion 1propels itself forward. When switch lever portion 10 is pushed down inthe left and right direction, as described above, switch lever portion10 controls driving motors 38A and 38B inside rotary shaft bodies 2A and2B so that the direction of suction port portion 1 is changed to thedirection in which switch lever portion 10 is pushed down.

That is, when switch lever portion 10 is pushed down in the rightdirection, only left driving motor 38B on the user side rotates in thepositive direction. For this reason, it is possible to easily change thedirection of suction port portion 1 to the right direction. At thistime, when switch portion 39A of rotary shaft body 2A and switch portion39B of rotary shaft body 2B are interlocked with each other so thatright driving motor 38A on the user side rotates in a direction oppositeto the rotation direction of driving motor 38B, it is possible to moreeasily change the direction of suction port portion 1 to the rightdirection. In the same manner, when switch portion 39A of rotary shaftbody 2A and switch portion 39B of rotary shaft body 2B are interlockedwith each other so that right driving motor 38A on the user side rotatesslower than driving motor 38B, it is possible to more easily change thedirection of suction port portion to the right direction. In any case,there is a difference in the rotation speed between rotary shaft bodies2A and 2B.

On the contrary, in order to further change the direction of suctionport portion 1 to the left direction, switch portion 39A of rotary shaftbody 2A and switch portion 39B of rotary shaft body 2B are interlockedwith each other as below. Switch portion 39A of rotary shaft body 2A andswitch portion 39B of rotary shaft body 2B are interlocked with eachother so that only right driving motor 38A on the user side rotates inthe positive direction, left driving motor 38B on the user side rotatesin a direction opposite to the rotation direction of driving motor 38A,or left driving motor 38B on the user side rotates more slowly thandriving motor 38A when switch lever portion 10 is pushed down in theleft direction.

That is, in this embodiment, rotation speed difference generatingmechanisms are separately disposed in each of rotary shaft bodies 2A and2B, and include separately rotating driving motors 38A and 38B, rotaryshaft body switch portions 39A and 39B, and switch lever portion 10.

As described above, in this embodiment, the direction of suction portportion 1 can be changed by generating a difference in the rotationspeed between two rotary shaft bodies 2A and 2B. For this reason, it ispossible to reduce a burden applied to an arm or wrist upon changing thedirection of suction port portion 1 in the left and right direction.

In this embodiment, suction port portion 1 propels itself in accordancewith the rotation of rotary shaft bodies 2A and 2B. For this reason,since suction port portion 1 propels itself forward or backward during acleaning operation, it is possible to reduce the burden during thecleaning operation.

In this embodiment, suction port portion 1 propels itself in accordancewith the rotation of rotary shaft bodies 2A and 2B. For this reason,since there is a difference in the rotation speed between two rotaryshaft bodies 2A and 2B, it is possible to reduce the burden applied tothe arm or wrist upon changing the direction of suction port portion 1.

In this embodiment, driving motor 4 is disposed inside each of rotaryshaft bodies 2A and 2B. For this reason, it is possible to decrease thesize of suction port portion 1 and to easily handle suction port portion1 in a narrow space. In addition, it is possible to dispose rotary brushunit 2 in substantially the entire width of suction port portion 1, andto improve a cleaning performance for cleaning a side wall.

In this embodiment, handle portion 11 includes switch lever portion 10which is operable in the left and right direction, and the rotation oftwo rotary shaft bodies 2A and 2B of rotary brush unit 2 is controlledso that the direction of suction port portion 1 is changed to thedirection in which switch lever portion 10 is operated. For this reason,it is possible to change the direction of suction port portion 1 just byusing a finger tip without performing a large action in which handleportion 11 is twisted or pushed down.

Second Embodiment

FIG. 4 is an entire perspective view showing the electric vacuum cleaneraccording to a second embodiment of the invention. This embodiment isdifferent from the first embodiment in that switch lever portion 10 isnot provided. Instead of switch lever portion 10, handle portion 11which is twistable in the left and right direction is provided. Therotation speed of two rotary shaft bodies 2A and 2B disposed in rotarybrush unit 2 inside suction port portion 1 is controlled through theelectric controller (not shown) so that the direction of suction portportion 1 is changed to the twisting direction of handle portion 11.When the twisting amount becomes large, the difference in the rotationspeed between rotary shaft bodies 2A and 2B becomes large, and theturning amount becomes large. In the case where handle portion 11 is nottwisted, suction port portion rotates forward. Since the otherconfigurations are same as those of the first embodiment, detaileddescription thereof will be omitted.

As described above, in this embodiment, handle portion 11 is twistablein the left and right direction. When handle portion 11 is twisted inthe left and right direction, the rotation of two rotary shaft bodies 2Aand 2B of rotary brush unit 2 is controlled so that the direction ofsuction port portion 1 is changed to the twisting direction of handleportion 11. Accordingly, it is possible to change the self-propellingdirection of the suction port portion while having the same feeling ofoperation as with a general cleaner having an oscillation mechanism.

Third Embodiment

FIG. 5 is a plan view showing rotary brush unit 2 inside suction portportion 1 of the electric vacuum cleaner according to a third embodimentof the invention. Rotary shaft bodies 2A and 2B constituting rotarybrush unit 2 are rotatably connected to each other through connectionportion 30. Connection portion 30 is formed as a simple bearing, and adifference in the rotation speed between rotary shaft bodies 2A and 2Bis absorbed by connection portion 30. Brush 3 is attached to surfaces ofrotary shaft bodies 2A and 2B.

Stiff brushes 3A depicted by the solid line are attached topredetermined ranges 101 of rotary brush unit 2. Soft brush 3B depictedby the dotted line is attached to predetermined ranges 102 at the centerof rotary brush unit 2. Since the other configurations are the same asthose of the first embodiment, detailed description thereof will beomitted.

With such a configuration, since a large self-propelling force isgenerated at a position far from the turning center, it is possible tomore efficiently turn suction port portion 1.

In this embodiment, the direction of the suction port portion is changedby generating a difference in the rotation speed between the drivingmotors using switch lever portion 10 of the first embodiment or handleportion 11B, which is twistable, of the second embodiment. At this time,in this embodiment, since the brush 3 includes stiff brushes 3A in thevicinity of both ends of rotary brush unit 2 and soft brushes 3B in thevicinity of the center thereof, it is possible to more efficiently turnsuction port portion 1.

As described above, in this embodiment, the stiffness of each of thebrushes 3 in the vicinity of both ends of rotary brush unit 2 is set tobe larger than that in the vicinity of the center thereof. Accordingly,since it is possible to improve the direction changing force of suctionport portion 1, it is possible to change the self-propelling directioneven on a floor surface having a high resistance such as a deep carpet.

Fourth Embodiment

FIG. 6 is a plan view showing rotary brush unit 2 inside suction portportion 1 of the electric vacuum cleaner according to a fourthembodiment of the invention. In rotary shaft bodies 2A and 2Bconstituting rotary brush unit 2, the outer diameter of range 110 in thevicinity of the center of rotary brush unit 2 is small, and the outerdiameter becomes large toward both ends. The length of brush 3 attachedto rotary shaft bodies 2A and 2B becomes shorter as the outer diametersof rotary shaft bodies 2A and 2B become larger. That is, in each ofrotary shaft bodies 2A and 2B, brush 3 includes brushes 3C and 3D ofwhich the lengths becomes short in a direction from the center to bothends. Accordingly, as depicted by one-dot dashed line P1, the outerdiameter of brush 3 up to the end of the bristle is substantiallyuniform throughout the entire width of the rotary brush unit 2. Sincethe other configurations are same as those of the first embodiment,detailed description thereof will be omitted.

With such a configuration, since the brush is hardly pushed down due tothe short length of the brush, it is possible to improve theself-propelling force at both ends of rotary brush unit 2 even in thecase of using a brush formed of the same material. That is, it ispossible to more efficiently turn suction port portion 1.

In this embodiment, the direction of the suction port portion is changedby generating a difference in the rotation speed between the drivingmotors using switch lever portion 10 of the first embodiment or handleportion 11B, which is twistable, of the second embodiment. At this time,in this embodiment, since brush 3 includes brushes 3C and 3D of whichthe lengths become short in a direction from the center of rotary brushunit 2 to both ends thereof, it is possible to more efficiently turnsuction port portion 1.

As described above, in this embodiment, the outer diameter of each ofrotary shaft bodies 2A and 2B in the vicinity of both ends of rotarybrush unit 2 is set to be larger than that in the vicinity of the centerthereof. In addition, the length of each of brushes 3 in the vicinity ofboth ends of rotary brush unit 2 is set to be shorter than that in thevicinity of the center thereof, and the outer diameter of each ofbrushes 3 up to the end of the bristle in the vicinity of both ends ofrotary brush unit 2 is set to be same as that in the vicinity of thecenter thereof. Accordingly, it is possible to improve the directionchanging force of suction port portion 1, and to change theself-propelling direction even on a floor surface having a large slidingresistance such as a deep carpet. Further, since the outer diameter ofeach of brushes 3 up to the end of the bristle is set to be uniform, itis possible to have uniform contact with a floor surface. Accordingly,it is possible to obtain a uniform suction function and a uniformself-propelling function throughout the entire width of rotary brushunit 2.

Fifth Embodiment

FIG. 7 is a plan view showing rotary brush unit 2 inside suction portportion 1 of the electric vacuum cleaner according to a fifth embodimentof the invention. In brush 3 attached to the surfaces of rotary shaftbodies 2A and 2B constituting rotary brush unit 2, the length of brush 3is short in range 110 in the vicinity of the center of rotary brush unit2, and becomes longer toward both ends. The outer diameter of brush 3 upto the end of the bristle is depicted by one-dot chain line P2. That is,brush 3 includes brushes 3E and 3F which are respectively disposed inrotary shaft bodies 2A and 2B so that the lengths thereof become longerin a direction from the center of rotary brush unit 2 to both endsthereof. Since the other configurations are same as those of the firstembodiment, detailed description thereof will be omitted.

With such a configuration, brush 3 at both ends of rotary brush unit 2strongly comes into contact with the floor surface to thereby generate alarge self-propelling force. As a result, it is possible to moreefficiently turn suction port portion 1.

In this embodiment, the direction of the suction port portion can bechanged by generating a difference in the rotation speed between thedriving motors using switch lever portion 10 of the first embodiment orhandle portion 11B, which is twistable, of the second embodiment. Atthis time, in this embodiment, since brush 3 includes brushes 3E and 3Fof which the lengths become longer in a direction from the center ofrotary brush unit 2 to both ends thereof, it is possible to moreefficiently turn suction port portion 1.

As described above, in this embodiment, the length of each of brushes 3in the vicinity of both ends of rotary brush unit 2 is set to be longerthan that in the vicinity of the center thereof. Accordingly, since itis possible to improve the direction changing force of suction portportion 1, it is possible to change the self-propelling direction evenon a floor surface having a large resistance such as a deep carpet.Further, since the distance from the center of the attachment portion ofbrush 3 is uniform, it is possible to easily perform a transplantingoperation using an automatic machine.

Sixth Embodiment

FIG. 8 is a plan view showing rotary brush unit 2 inside suction portportion 1 of the electric vacuum cleaner according to a sixth embodimentof the invention. In the same manner as the above-described embodiments,brush 3 is attached to the surfaces of rotary shaft bodies 2A and 2Bconstituting rotary brush unit 2. The pitch between brushes 3 attachedto predetermined ranges 120 of both ends of rotary brush unit 2 isnarrow. The pitch at predetermined range 121 in the vicinity of thecenter of rotary brush unit 2 is wide. That is, brush 3 includeshigh-density brush 3G attached to both ends of rotary brush unit 2 andlow-density brush 3H attached to the vicinity of the center thereof.Since the other configurations are same as those of the firstembodiment, detailed description thereof will be omitted.

Accordingly, it is possible to generate a large self-propelling force atboth ends of rotary brush unit 2. For this reason, it is possible tomore efficiently turn suction port portion 1.

In this embodiment, the direction of the suction port portion is changedby generating a difference in the rotation speed between the drivingmotors using switch lever portion 10 of the first embodiment or handleportion 11B, which is twistable, of the second embodiment. At this time,in this embodiment, since brush 3 includes high-density brush 3Gattached to both ends of rotary brush unit 2 and low-density brush 3Hattached to the vicinity of the center thereof, it is possible to moreefficiently turn suction port portion 1.

As described above, in this embodiment, the density of each of brushes 3in the vicinity of both ends of rotary brush unit 2 is set to be higherthan that in the vicinity of the center thereof. Particularly, brush 3of each of rotary shaft bodies 2A and 2B is formed with a comb toothshape, and the pitch of the comb tooth shape of each of brushes 3 in thevicinity of both ends of rotary brush unit 2 is set to be denser thanthat of each of brushes 3 in the vicinity of the center thereof.Accordingly, since it is possible to improve the direction changingforce of suction port portion 1, it is possible to change theself-propelling direction even on a floor surface having a highresistance such as a deep carpet. In addition, since it is possible tomake the type, stiffness, and length of the bristles of brush 3 uniformthroughout the entire width of brush unit 2, it is possible to improvethe productivity.

Seventh Embodiment

FIG. 9 is a plan view showing rotary brush unit 2 inside suction portportion 1 of the electric vacuum cleaner according to a seventhembodiment of the invention. In the same manner as the above-describedembodiments, brush 3 is attached to the surfaces of rotary shaft bodies2A and 2B constituting rotary brush unit 2. In brushes 3, four lines ofbrushes 3I are respectively attached to predetermined ranges 130 of bothends of rotary brush unit 2. Two lines of brushes 3J are attached torange 131 in the vicinity of the center of rotary brush unit 2. Sincethe other configurations are same as those of the first embodiment,detailed description thereof will be omitted.

Accordingly, it is possible to generate a large self-propelling force atboth ends of rotary brush unit 2. For this reason, it is possible tomore efficiently turn suction port portion 1.

In this embodiment, the direction of the suction port portion is changedby generating a difference in the rotation speed between the drivingmotors using switch lever portion 10 of the first embodiment or handleportion 11B, which is twistable, of the second embodiment. At this time,in this embodiment, since brush 3 includes four lines of brushes 3I inboth ends of rotary brush unit 2 and two lines of brushes 3J in thevicinity of the center thereof, it is possible to more efficiently turnsuction port portion 1.

As described above, brushes 3 of rotary shaft bodies 2A and 2B areformed in a stripe shape, and the number of lines of brushes 3 in thevicinity of both ends of rotary brush unit 2 is larger than that ofbrushes 3 in the vicinity of the center thereof. Accordingly, since itis possible to improve the direction changing force of suction portportion 1, it is possible to change the self-propelling direction evenon a floor surface having a high resistance such as a deep carpet. Inaddition, since it is possible to make the type, stiffness, length, andtransplanting pitch of the bristles of brush 3 uniform throughout theentire width of brush unit 2, it is possible to improve theproductivity.

As described above, the electric vacuum cleaner according to theinvention includes the cleaner body portion which has the electricblower for generating a suction wind; the suction port portion whichsucks dust together with the suction wind; the handle portion whichmoves the suction port portion; the rotary brush unit which is disposedinside the suction port portion and in which two rotary shaft bodieseach having a brush are disposed in series; the rotary brush unitdriving portion which separately rotates each of the rotary shaftbodies; and the rotation speed difference generating mechanism whichgenerates a difference in the rotation speed between two rotary shaftbodies.

With such a configuration, it is possible to reduce the burden appliedto the arm or wrist upon changing the direction of suction port portionin the left and right direction.

In the invention, the suction port portion propels itself in accordancewith the rotation of the rotary shaft bodies. With such a configuration,since the suction port portion propels itself forward or backward duringthe cleaning operation, it is possible to reduce the burden applied tothe arm or wrist.

In the invention, the rotary brush unit driving portion is configured asthe driving motor disposed inside each of the rotary shaft bodies. Withsuch a configuration, it is possible to decrease the size of the suctionport portion and to easily handle the suction port portion in a narrowspace. In addition, it is possible to dispose the rotary brush unit insubstantially the entire width of the suction port portion, and toimprove the cleaning performance for cleaning a side wall.

In the invention, the handle portion includes the switch lever portionwhich is operable in the left and right direction, and controls therotation of two rotary shaft bodies of the rotary brush unit so that thedirection of the suction port portion is changed to the operationdirection of the switch lever portion. With such a configuration, it ispossible to change the direction of the suction port portion just byusing a finger tip without performing a large action in which the handleportion is twisted or pushed down.

In the invention, the handle portion is twistable in the left and rightdirection. When the handle portion is twisted in the left and rightdirection, the rotation of two rotary shaft bodies of the rotary brushunit is controlled so that the direction of the suction port portion ischanged to the twisting direction of the handle portion. With such aconfiguration, it is possible to change the self-propelling direction ofthe suction port portion while having the same feeling of operation aswith a general cleaner having an oscillation mechanism.

In the invention, the stiffness of each of the brushes in the vicinityof both ends of the rotary brush unit is set to be larger than that inthe vicinity of the center thereof. With such a configuration, since itis possible to improve the direction changing force of the suction portportion, it is possible to change the self-propelling direction even ona floor surface having a high resistance such as a deep carpet.

In the invention, the outer diameter of each of the rotary shaft bodiesin the vicinity of both ends of the rotary brush unit is set to belarger than that in the vicinity of the center thereof. In addition, thelength of each of the brushes in the vicinity of both ends of the rotarybrush unit is set to be shorter than that in the vicinity of the centerthereof, and the outer diameter of each of the brushes up to the end ofthe bristle in the vicinity of both ends of the rotary brush unit is setto be same as that in the vicinity of the center thereof

With such a configuration, it is possible to improve the directionchanging force of the suction port portion, and to change theself-propelling direction even on a floor surface having a large slidingresistance such as a deep carpet. Further, since the outer diameter ofthe brush up to the end of the bristle is set to be uniform, it ispossible to have uniform contact with a floor surface. Accordingly, itis possible to obtain a uniform suction function and a uniformself-propelling function throughout the entire width of the rotary brushunit.

In the invention, the length of each of the brushes in the vicinity ofboth ends of the rotary brush unit is set to be longer than that in thevicinity of the center thereof With such a configuration, since it ispossible to improve the direction changing force of the suction portportion, it is possible to change the self-propelling direction even ona floor surface having a large resistance such as a deep carpet.Further, since the distance from the center of the attachment portion ofthe brush is uniform, it is possible to easily perform a transplantingoperation using an automatic machine.

In the invention, the density of each of the brushes in the vicinity ofboth ends of the rotary brush unit is set to be higher than that in thevicinity of the center thereof With such a configuration, since it ispossible to improve the direction changing force of the suction portportion, it is possible to change the self-propelling direction even ona floor surface having a high resistance such as a deep carpet. Inaddition, since it is possible to make the type, stiffness, and lengthof the bristles of the brush uniform throughout the entire width of thebrush unit, it is possible to improve the productivity.

In the invention, the brushes of each of the rotary shaft bodies areformed with a comb tooth shape, and the pitch of the comb tooth shape ofeach of the brushes in the vicinity of both ends of the rotary brushunit is set to be denser than that in the vicinity of the centerthereof.

With such a configuration, since it is possible to improve the directionchanging force of the suction port portion, it is possible to change theself-propelling direction even on a floor surface having a highresistance such as a deep carpet. In addition, since it is possible tomake the type, stiffness, and length of the bristles of the brushuniform throughout the entire width of the brush unit, it is possible toimprove the productivity.

In the invention, the brush of the rotary shaft body is formed in astripe shape, and the number of lines of the brushes in the vicinity ofboth ends of the rotary brush unit is set to be larger than that in thevicinity of the center thereof.

With such a configuration, since it is possible to improve the directionchanging force of the suction port portion, it is possible to change theself-propelling direction even on a floor surface having a highresistance such as a deep carpet. In addition, since it is possible tomake the type, stiffness, and length of the bristles of the brushuniform throughout the entire width of the brush unit, it is possible toimprove the productivity.

As described above, the advantage of the invention is particularlyapparent in a heavy electric vacuum cleaner such as an upright cleaner.For this reason, it is possible for even an old person, a woman, or achild to perform a cleaning operation using the electric vacuum cleaner,and to suppress fatigue even during a lengthy cleaning operation. Inaddition, regardless of age, sex or whether used at home or the office,it is possible to reduce the effort involved during a cleaningoperation.

1. An electric vacuum cleaner comprising: a cleaner body portion whichhas an electric blower for generating a suction wind; a suction portportion which sucks dust together with the suction wind; a handleportion which moves the suction port portion; a rotary brush unit whichis disposed inside the suction port portion and in which two rotaryshaft bodies each having a brush are disposed in series; a rotary brushunit driving portion which separately rotates each of the rotary shaftbodies; and a rotation speed difference generating mechanism whichgenerates a difference in the rotation speed between the two rotaryshaft bodies.
 2. The electric vacuum cleaner of claim 1, wherein thesuction port portion propels itself in accordance with the rotation ofthe rotary shaft bodies.
 3. The electric vacuum cleaner of claim 1,wherein the rotary brush unit driving portion is configured as a drivingmotor which is disposed inside each of the rotary shaft bodies.
 4. Theelectric vacuum cleaner of claim 1, wherein the handle portion includesa switch lever portion which is operable in the left and rightdirection, and controls the rotation of the two rotary shaft bodies ofthe rotary brush unit so that a direction of the suction port portion ischanged to the operation direction of the switch lever portion.
 5. Theelectric vacuum cleaner of claim 1, wherein the handle portion istwistable in the left and right direction, and wherein when the handleportion is twisted in the left and right direction, the rotation of thetwo rotary shaft bodies of the rotary brush unit is controlled so that adirection of the suction port portion is changed to the twistingdirection of the handle portion.
 6. The electric vacuum cleaner of claim1, wherein stiffness of each of the brushes in the vicinity of both endsof the rotary brush unit is set to be harder than that in the vicinityof the center thereof.
 7. The electric vacuum cleaner of claim 1,wherein an outer diameter of each of the rotary shaft bodies at bothends of the rotary brush unit is set to be larger than that in thevicinity of the center, wherein a length of each of the brushes in thevicinity of both ends of the rotary brush unit is set to be shorter thanthat in the vicinity of the center thereof, and wherein an outerdiameter of each of the brushes up to the end of its bristles in thevicinity of both ends of the rotary brush unit is set to be same as thatin the vicinity of the center thereof
 8. The electric vacuum cleaner ofclaim 1, wherein a length of each of the brushes in the vicinity of bothends of the rotary brush unit is set to be longer than that in thevicinity of the center thereof.
 9. The electric vacuum cleaner of claim1, wherein a density of each of the brushes in the vicinity of both endsof the rotary brush unit is set to be higher than that in the vicinityof the center thereof.
 10. The electric vacuum cleaner of claim 9,wherein the brushes of the rotary shaft bodies are formed in a combtooth shape, and a pitch of the comb tooth shape of each of the brushesin the vicinity of both ends of the rotary brush unit is set to benarrower than that in the vicinity of the center thereof.
 11. Theelectric vacuum cleaner of claim 9, wherein the brushes of the rotaryshaft bodies are formed in a stripe shape, and the number of lines ofthe brushes in the vicinity of both ends of the rotary brush unit is setto be larger than that in the vicinity of the center thereof.